Loose Bodies

It is convenient to describe the varieties of loose bodies under two
heads: those composed of fibrin, and those composed of organised
connective tissue.

Fibrinous Loose Bodies (Corpora oryzoidea).—These are homogeneous or
concentrically laminated masses of fibrin, sometimes resembling rice
grains, melon seeds, or adhesive wafers, sometimes quite irregular in
shape. Usually they are present in large numbers, but sometimes there is
only one, and it may attain considerable dimensions. They are not
peculiar to joints, for they are met with in tendon sheaths and bursÃ¦,
and their origin from synovial membrane may be accepted as proved. They
occur in tuberculosis, arthritis deformans, and in Charcot's disease,
and their presence is almost invariably associated with an effusion of
fluid into the joint. While they may result from the coagulation of
fibrin-forming elements in the exudate, their occurrence in tuberculous
hydrops would appear to be the result of coagulation necrosis, or of
fibrinous degeneration of the surface layer of the diseased synovial
membrane. However formed, their shape is the result of mechanical
influences, and especially of the movement of the joint.

Clinically, loose bodies composed of fibrin constitute an unimportant
addition to the features of the disease with which they are associated.
They never give rise to the classical symptoms associated with impaction
of a loose body between the articular surfaces. Their presence may be
recognised, especially in the knee, by the crepitating sensation
imparted to the fingers of the hand grasping the joint while it is
flexed and extended by the patient.

The treatment is directed towards the disease underlying the hydrops.
If it is desired to empty the joint, this is best done by open
incision.

Fig. 166.—Radiogram of Multiple Loose Bodies in
Knee-joint and Semi-membranosus Bursa in a man Ã¦t.Â 38.

(Mr. J.Â W.
Dowden's case.)

Bodies composed of Organised Connective Tissue.—These are
comparatively common in joints that are already the seat of some chronic
disease, such as arthritis deformans, Charcot's arthropathy, or synovial
tuberculosis. They take origin almost exclusively from an erratic
overgrowth of the fringes of the synovial membrane, and may consist
entirely of fat, the arborescent lipoma (Fig.Â 159) being the most
pronounced example of this variety. Fibrous tissue or cartilage may
form in one or more of the fatty fringes and give rise to hard nodular
masses, which may attain a considerable size, and in course of time may
undergo ossification.

Like other hypertrophies on a free surface, they tend to become
pedunculated, and so acquire a limited range of movement. The pedicle
may give way and the body become free. In this condition it may wander
about the joint, or lie snugly in one of its recesses until disturbed by
some sudden movement. A loose body free in a joint is capable of growth,
deriving the necessary nutriment from the surrounding fluid. The size
and number of the bodies vary widely. Single specimens have been known
to attain the size of the patella. The smaller varieties may number
considerably over a hundred.

aÂ b

Fig. 167.—Loose Body from Knee-joint of man Ã¦t.Â 25. Natural size.

a = Convex surface. b = Concave surface.

In arthritis deformans a rarer type of loose body is met with, a portion
of the lipping of one of the articular margins being detached by injury.
In Charcot's disease, bodies composed of bone are formed in relation to
the capsular and other ligaments, and may be made to grate upon one
another.

The clinical features in this group are mainly those of the disease
which has given rise to the loose bodies, and it is exceptional to meet
with symptoms from impaction of the body between the articular surfaces.
Treatment is to be directed towards the primary disease in the joint, as
well as to the removal of the loose bodies.

Fig. 168.—Multiple partially ossified
Chondromas of Synovial Membrane, from Shoulder-joint, the seat of
arthritis deformans, from a man Ã¦t.Â 35.

Loose Bodies in Joints which are otherwise healthy.—It is in joints
otherwise healthy that loose bodies causing the classical symptoms and
calling for operative treatment are most frequently met with. They occur
chiefly in the knee and elbow of healthy males under the age of thirty.
The complaint may be of vague pains, of occasional cracking on moving
the joint, or of impairment of function—usually an inability to extend
or flex the joint completely. In many cases a clear account is given of
the symptoms which arise when the body is impacted between the articular
surfaces, namely, sudden onset of intense sickening pain, loss of power
in the limb and locking of the joint, followed by effusion and other
accompaniments of a severe sprain. On some particular movement, the
body is disengaged, the locking disappears, and recovery takes place.
Attacks of this kind may recur at irregular intervals, during a period
of many years. On examining the joint, it is usually found to contain
fluid, and there may be points of special tenderness corresponding to
the ligaments that have been overstretched. In cases in which there has
been recurrent attacks of locking, the ligaments become slack, the joint
is wobbly, and the quadriceps is wasted. The patient himself, or the
surgeon, may discover the loose body and feel it roll beneath his
fingers, especially if it is lodged in the supra-patellar pouch in the
knee, or on one or other side of the olecranon in the elbow. In most
instances the patient has carefully observed his own symptoms, and is
aware not only of the existence of the loose body, but of its erratic
appearance at different parts of the joint. This feature serves to
differentiate the lesions from a torn medial meniscus in which the pain
and tenderness are always in the same spot. As the body usually contains
bone, it is recognisable in a skiagram.

Fig. 169.—Multiple Cartilaginous Loose Bodies
from Knee-joint.

There are two methods of removing the body; the first and simpler
method is applicable when the body can be palpated, usually in the
supra-patellar pouch; it is preferably transfixed by a needle and can
then be removed through a small incision; otherwise, the joint must be
freely opened and explored, firstly to find the body and further to
remove it.

The characters of this type of loose body are remarkably constant. It is
usually solitary, about the size of a bean or almond, concavo-convex in
shape, the convex aspect being smooth like an articular surface, the
concave aspect uneven and nodulated and showing reparative changes,
healing over of the raw surface, and the new formation of fibrous
tissue, hyaline cartilage and bone, the necessary nutriment being
derived from the synovial fluid (Fig.Â 167). The body is sometimes found
to be lodged in a defect or excavation in one of the articular surfaces,
usually the medial condyle of the femur, from which it is readily
shelled out by means of an elevator. It presents on section a layer of
articular cartilage on the convex aspect and a variable thickness of
spongy bone beneath this.

The origin of these bodies is one of the most debated questions in
surgical pathology; they obviously consist of a portion of the articular
surface of one of the bones, but how this is detached still remains a
mystery; some maintain that it is purely traumatic; KÃ¶nig regards them
as portions of the articular surface which have been detached by a
morbid process which he calls “osteochondritis dessicans.”

Multiple Chondromas and Osteomas of the Synovial Membrane.—In this
rare type of loose body, the surface of the synovial membrane is studded
with small sessile or pedunculated tumours composed of pure hyaline
cartilage, or of bone, or of transition stages between cartilage and
bone. They are pearly white in colour, pitted and nodular on the
surface, rarely larger than a pea, although when compressed they may
cake into masses of considerable size. With the movements of the joint
many of the tumours become detached and lie in the serous exudate
excited by their presence. They are found also in the diverticula of the
synovial membrane, in the shoulder in the downward prolongation along
the tendon of the biceps, in the hip in the bursal extension beneath the
psoas.

The patient complains of increasing disability of the limb, movements of
the joint becoming more and more restricted and painful. There is
swelling corresponding to the distended capsule of the joint, and on
palpation the bodies moving under the fingers yield a sensation as of
grains of rice shifting in a bag. If the bodies are so numerous as to be
tightly packed together, the impression is that of a plastic mass having
the shape of the synovial sac. The stiffness and the cracking on
movement may suggest arthritis deformans, but the X-ray appearances make
the diagnosis an easy one. We have observed two cases of this affection
in the knee-joint of adult women, one in the shoulder-joint of an adult
male (Fig.Â 168), and Caird has observed one in the hip. The treatment
consists in opening the joint by free incision and removing the bodies.

Displacement of the menisci of the knee is referred to with injuries
of that joint.